Imaging of Endocarditis and Cardiac Device-Related Infections: An Update.

IE is a deadly disease requiring prompt diagnosis for adequate patient's management. The diagnosis requires the integration of clinical signs, microbiology data and imaging data and proper discussion within a multidisciplinary team, the endocarditis team. Since the introduction of 18F-FDG-PET/CT and WBC SPECT/CT in the diagnostic algorithm of PVE the nuclear medicine imaging specialists is active part of the Endocarditis Team, requiring proper knowledge of dedicated imaging acquisition protocols, expertise for imaging reading and interpretations to select the best test or combination of tests for each specific clinical situation. In this manuscript, we will review the main technical aspects of each imaging procedure, the most recent literature with specific regards to special challenging populations and provide clinical examples.

Visual and semiquantitative assessment of cranial artery inflammation with FDG-PET/CT in giant cell arteritis.

BACKGROUND AND AIM: Assessing cranial artery inflammation plays an important role in the diagnosis of cranial giant cell arteritis (C-GCA). However, current diagnostic tests are limited. The use of fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT imaging is an established tool for assessing large vessel inflammation but is currently not used for assessment of the cranial arteries. This study aimed to evaluate the accuracy of FDG-PET/CT in the diagnosis of biopsy proven C-GCA and its relation to clinical presentation. METHODS: This retrospective case control study included temporal artery biopsy (TAB) positive C-GCA patients and age- and sex-matched controls. FDG-PET/CT scans were performed according to EANM/EARL guidelines, visually assessed by an experienced nuclear medicine physician, and semiquantitatively assessed using the maximum standardised uptake value (SUVmax). The visual and semiquantitative assessments were performed on the temporal arteries, maxillary arteries, vertebral arteries, and occipital arteries. Clinical signs and symptoms were scored for comparison. RESULTS: A total of 24 C-GCA patients and 24 controls were included in the study. Visual analysis revealed an 83% sensitivity and a 75% specificity. Receiver operating characteristic (ROC) analysis of the semiquantitative assessment revealed a 79% sensitivity and a 92% specificity when measuring SUVmax in the cranial arteries. Visual and semiquantitative assessments showed moderate agreement (Fleiss kappa 0.55). There was a positive correlation between the number of cranial symptoms and the SUVmax in the vertebral artery. CONCLUSION: FDG-PET/CT can reliably diagnose C-GCA by assessing cranial artery inflammation using SUVmax. Extending the use of FDG-PET/CT to include assessment of the cranial arteries may improve its diagnostic value in GCA and provide a suitable alternative to TAB. Moderate agreement between visual and semiquantitative assessment methods suggest diagnostic accuracy may be improved by further standardisation.

Changes in cerebral oxygenation and cerebral blood flow during hemodialysis - A simultaneous near-infrared spectroscopy and positron emission tomography study.

Near-infrared spectroscopy (NIRS) is used to monitor cerebral tissue oxygenation (rSO2) depending on cerebral blood flow (CBF), cerebral blood volume and blood oxygen content. We explored whether NIRS might be a more easy applicable proxy to [15O]H2O positron emission tomography (PET) for detecting CBF changes during hemodialysis. Furthermore, we compared potential determinants of rSO2 and CBF. In 12 patients aged ≥ 65 years, NIRS and PET were performed simultaneously: before (T1), early after start (T2), and at the end of hemodialysis (T3). Between T1 and T3, the relative change in frontal rSO2 (ΔrSO2) was -8 ± 9% (P = 0.001) and -5 ± 11% (P = 0.08), whereas the relative change in frontal gray matter CBF (ΔCBF) was -11 ± 18% (P = 0.009) and -12 ± 16% (P = 0.007) for the left and right hemisphere, respectively. ΔrSO2 and ΔCBF were weakly correlated for the left (ρ 0.31, P = 0.4), and moderately correlated for the right (ρ 0.69, P = 0.03) hemisphere. The Bland-Altman plot suggested underestimation of ΔCBF by NIRS. Divergent associations of pH, pCO2 and arterial oxygen content with rSO2 were found compared to corresponding associations with CBF. In conclusion, NIRS could be a proxy to PET to detect intradialytic CBF changes, although NIRS and PET capture different physiological parameters of the brain.

The importance of left ventricular function for long-term outcome after primary percutaneous coronary intervention.

BACKGROUND: In the present study we sought to determine the long-term prognostic value of left ventricular ejection fraction (LVEF), assessed by planar radionuclide ventriculography (PRV), after ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PPCI). METHODS: In total 925 patients underwent PRV for LVEF assessment after PPCI for myocardial infarction before discharge from the hospital. PRV was performed with a standard dose of 500 Mbq of 99mTc-pertechnetate. Average follow-up time was 2.5 years. RESULTS: Mean (+/- SD) age was 60 +/- 12 years. Mean (+/- SD) LVEF was 45.7 +/- 12.2 %. 1 year survival was 97.3 % and 3 year survival was 94.2 %. Killip class, multi vessel-disease, previous cardiovascular events, peak creatin kinase and its MB fraction, age and LVEF proved to be univariate predictors of mortality. When entered in a forward conditional Cox regression model age and LVEF were independent predictors of 1 and 3 year mortality. CONCLUSION: LVEF assessed by PRV is a powerful independent predictor of long term mortality after PPCI for STEMI.

Incidental congenital coronary artery vascular fistulas in adults: Evaluation with adenosine-13N-ammonia PET-CT.

AIM: To assess the functionality of congenital coronary artery fistulas (CAFs) using adenosine stress 13N-ammonia positron emission tomography computed tomography (PET-CT). METHODS: Congenital CAFs were incidentally detected during coronary angiography (CAG) procedures in 11 adult patients (six males and five females) with a mean age of 64.3 years (range 41-81). Patients were collected from three institutes in the Netherlands. The characteristics of the fistulas (origin, pathway and termination), multiplicity of the origins and pathways of the fistulous vessels were assessed by CAG. Five patients underwent adenosine pharmacologic stress 13N-ammonia PET-CT to assess myocardial perfusion and the functional behavior of the fistula. RESULTS: Eleven patients with 12 CAFs, 10 unilateral and one bilateral, originating from the left anterior descending coronary artery (n = 8), right coronary artery (n = 2) and circumflex (n = 2). All fistulas were of the vascular type, terminating into either the pulmonary artery (n = 11) or coronary sinus (n = 1). The CAG delineated the characteristics of the fistula (origin, pathway and termination). Multiplicity of the origins and pathways of the fistulous vessels were common in most fistulas (8/12, 67% and 9/12, 75%, respectively). Multiplicity was common among the different fistula components (23/36, 64%). Adenosine pharmacologic stress 13N-ammonia PET-CT revealed normal myocardial perfusion and ejection fraction in all but one patient, who showed a reduced ejection fraction. CONCLUSION: PET-CT may be helpful for assessing the functional status of congenital CAFs in selected patients regarding clinical decision-making. Studies with a larger patient series are warranted.

Fluorodeoxyglucose and C-Choline positron emission tomography for distinction of metastatic plexopathy and neuritis: a case report.

INTRODUCTION: Fluorodeoxyglucose positron emission tomography scanning has an established role in the diagnostic work-up of many malignant diseases and also in the evaluation of cancer treatment response. Fluorodeoxyglucose positron emission tomography may, however be non-specific as infectious processes are depicted as well. CASE PRESENTATION: We present a patient with longstanding leg pain and weakness due to plexopathy developed a few years after treatment for prostate cancer. Prostate-specific antigen was raised and magnetic resonance imaging showed contrast uptake in thickened sacral nerves, suspicious for metastasis. While fluorodeoxyglucose positron emission tomography showed increased uptake in the plexus region, (11)C-Choline- positron emission tomography did not show any uptake. It was concluded that the FDG uptake reflected plexus neuritis and no tumor. Treatment for pain relief was started. CONCLUSION: (11)C-Choline- positron emission tomography can be used to detect metastasis in patients with plexopathy suspicious for malignancy, while fluorodeoxyglucose positron emission tomography is more sensitive to inflammatory processes.

Electromechanical mapping of the left ventricle: possible tool for online decision making in the catheterization laboratory.

Clinical decision making in intervention cardiology often depends on information about the presence of myocardial viability and the extent of ischemia. Especially in the case of an occluded collaterally filled coronary branch, online decision making in selected patients may accelerate and improve patient care. The electromechanical NOGA mapping system offers the opportunity for online viability assessment. We describe two cases in which this diagnostic tool was used during daily practice. In our opinion, NOGA mapping can be helpful for 'online' viability evaluation in patients with an occluded collaterally filled coronary artery. In these patients, noninvasive viability evaluation may cause unnecessary delay in the overall treatment approach.